1. Field of the Invention
The present invention relates to the detection of chemical substances; and more particularly to method and system for determining the presence or absence of a target sample in an antibody/antigen mixture.
While the invention is subject to a wide range of applications it is especially suited for use in a system and method for rapidly determining whether a target substance is heroin, cocaine, or other illicit chemical; and will be particularly described in that connection.
2. Description of Related Art
In enforcing the prohibition against the possession of illicit substances, it is important that an accurate determination of a substance suspected of being illicit is made rapidly.
Without being able to obtain a rapid objective determination as to whether or not substances that are suspected of being or containing an illicit substance, customs agents, airport officials, or other drug enforcement officers either detain and embarrass innocent persons needlessly, or permit violators to evade being apprehended for fear of such wrongful detainment.
A well-known technique for detecting the presence of a wide variety of chemical substances uses antibody/antigen reactions. With this technique, microscopic particles, to which the antibody or antibody generator are chemically attached, are made to agglutinate or are inhibited from agglutinating in the presence of a particular target sample.
One type of agglutination reaction that is used for detecting the presence or absence of cocaine or heroin, for example, is known as latex agglutination. When the antibody and the target substance are first mixed, the result is a uniform milky substance. If cocaine or heroin is not present in the mixture, the antibodies and latex particles interact and combine. After a period of time many linkages are formed, which manifest themselves as visible clusters in the substances thus causing the mixture to lose its uniform milky texture. However, if cocaine or heroin is present in the mixture, the particles and the antibody generator do not combine and the uniform milky characteristic persists. The reaction of the mixture which results in the clusters and destruction of the uniform milky quality of the mixture is referred to as a negative result and the persistence of the milky characteristic, which is caused by the presence of heroin or cocaine, is referred to as a positive result.
As far as is known, prior art systems typically used for carrying out this procedure require several steps, which are not conducive to being used in the field. Also, the necessity of measuring the reagents in the exact proportions, and the necessity of maintaining a particular orientation during the flow of the mixed fluid, as well as requiring human judgement in determining the result, all contributed to the difficulty in carrying out the procedure involving antibody/antigen reactions.
In light of the foregoing, there is a need for a method and system for detecting illicit substances, which does not involve subjective human judgment, and which provides a definitive reliable response in a short period of time.